1. Field of the Invention
This invention relates to an anodizing process employing adjustable shields for suspended cathodes.
2. Description of the Prior Art
Suspended electrodes in electrolytic baths are employed as cathodes in metal plating installations and as anodes in anodizing installations. See British Pat. No. 665,599 and U.S. Pat. No. 2,833,710.
For optimum electroplating, it is important to control the ratio of surface area of anode-to-cathode. This control has been accomplished heretofore by increasing or decreasing the number of anodes which are employed in an electroplating bath. In some installations, where more precise control is demanded for product quality, a portion of the surface area of one or more anodes has been covered with tape to reduce the surface exposure of the taped anode. This procedure is labor intensive, although effective.
In hard anodizing installations, it is important to control the ratio of surface area of cathode-to-anode. If the ratio is too small, the anodizing rate is reduced. If the ratio is too large, local coating degradation known as "burning" may occur.
Accordingly, it is desirable to provide an effective, convenient means for adjusting the surface area of a suspended electrode which is maintained in effective electrolytic communication with an electrolytic bath whereby the surface area of the controlled electrode to the surface area of the parts undergoing treatment can be regulated.